Doping Ti to achieve microstructural refinement and strength enhancement in a high volume fraction Y2O3 dispersion strengthened Cu

Abstract

In this work, high volume fraction Y2O3 dispersion strengthened Ti-free and Ti-doped Cu samples were prepared by mechanical alloying, high temperature heat treatment and powder compact extrusion to study the role of alloying Ti element on microstructures, mechanical properties and electrical conductivity of the extruded samples. It is found that the addition of a small amount of 0.4 wt.%Ti effectively suppresses the coarsening of Y2O3 particles during material fabrication, which produces smaller and more uniform oxide particles distributed in a homogeneous ultrafine grained Cu matrix. However, a heterogeneous Cu matrix microstructure, consisting of elongated micrometer-scale Cu grains and equiaxed ultrafine Cu grains, is observed in the Ti-free sample due to significant coarsening of the Y2O3 particles. The different microstructural features of the two extruded samples lead to distinctively different mechanical behaviors and electrical conductivities. The energy dispersive X-ray spectrometry elemental and high resolution transmission electron microscopy analysis suggest that the stabilizing mechanisms of the Y2O3 particles involve both the segregation of Ti atoms to the surface layers of large Y2O3 particles and dissolution of Ti atoms into small Y2O3 particles to form complex particles.